Accepted Manuscript
Enhancing the acute psychological benefits of green exercise: An investigation ofexpectancy effects
Elliott P. Flowers, Paul Freeman, Valerie F. Gladwell
PII: S1469-0292(17)30799-9
DOI: 10.1016/j.psychsport.2018.08.014
Reference: PSYSPO 1415
To appear in: Psychology of Sport & Exercise
Received Date: 8 December 2017
Revised Date: 12 July 2018
Accepted Date: 28 August 2018
Please cite this article as: Flowers, E.P., Freeman, P., Gladwell, V.F., Enhancing the acutepsychological benefits of green exercise: An investigation of expectancy effects, Psychology of Sport &Exercise (2018), doi: 10.1016/j.psychsport.2018.08.014.
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service toour customers we are providing this early version of the manuscript. The manuscript will undergocopyediting, typesetting, and review of the resulting proof before it is published in its final form. Pleasenote that during the production process errors may be discovered which could affect the content, and alllegal disclaimers that apply to the journal pertain.
MANUSCRIP
T
ACCEPTED
ACCEPTED MANUSCRIPT
Enhancing the acute psychological benefits of green exercise: an investigation of expectancy
effects.
Author Note
Elliott P. Flowers, School of Sport, Rehabilitation and Exercise Sciences, University
of Essex; Paul Freeman, School of Sport, Rehabilitation and Exercise Sciences, University of
Essex; Valerie F. Gladwell, School of Sport, Rehabilitation and Exercise Sciences,
University of Essex.
This research was conducted as partial fulfilment for the requirements of a Doctorate
in Philosophy degree
Correspondence concerning this article should be addressed to Elliott P. Flowers,
School of Sport, Rehabilitation and Exercise Sciences, University of Essex.
United Kingdom.
Email [email protected]
Declaration of interest: none
MANUSCRIP
T
ACCEPTED
ACCEPTED MANUSCRIPT 1
Abstract
Objective: Exercising in the presence of a natural environment (termed green exercise) appears
to provide addition benefits compared to indoor exercise. We assessed the impact of a green
exercise promotional video on the acute psychological benefits of green-outdoor and indoor
exercise.
Design: Participants were randomly assigned to one of four groups. Two groups undertook green
exercise (with one of these groups watching a green exercise promotional video). The other two
groups undertook indoor exercise (with one of these groups watching the promotional video).
The green-outdoor and indoor exercise conditions were created to replicate those of a previous
study (Rogerson, Gladwell, Gallagher, & Barton, 2016b). The promotional video was designed
to highlight benefits of green exercise and was used to manipulate expectations of acute green
exercise.
Method: Participants (N = 60) completed 15-minutes of moderate-intensity cycling, with self-
esteem, vigour (dependent variables), and attitudes (manipulation check) assessed pre- and post-
activity. Measures of physical activity and green exercise levels were also recorded at baseline.
Results: The findings suggest that green exercise elicits greater psychological benefits than
indoor exercise, and those benefits can be increased via expectancy modification. In contrast,
the same expectancy modification suppressed the psychological benefits of cycling indoors.
Conclusions: A promotional video can further enhance the affective response to green exercise.
This may help to encourage future physical activity participation holding great promise for
researchers, practitioners and policy makers.
Keywords: green exercise, placebo, nocebo, vigour, self-esteem, attitude
MANUSCRIP
T
ACCEPTED
ACCEPTED MANUSCRIPTEXPECTANCY EFFECTS IN GREEN EXERCISE 1
Enhancing the acute psychological benefits of green exercise: an investigation of expectancy
effects.
Acute exercise enhances psychological well-being through a number of mechanisms
including reducing anxiety (Ensari, Greenlee, Motl, & Petruzzello, 2015; Petruzzello, Landers,
Hatfield, Kubitz, & Salazar, 1991; Stonerock, Hoffman, Smith, & Blumenthal, 2015), and
enhancing self-esteem (Fox, 2000; Rogerson, Brown, Sandercock, Wooller, & Barton, 2016;
Spence, McGannon, & Poon, 2005) and mood (Anderson & Brice, 2011; Berger & Motl, 2000;
Helfer, Elhai, & Geers, 2014; Petruzzello, Snook, Gliottoni, & Motl, 2009; Yeung, 1996). This is
supported by comprehensive reviews (Arent, Landers, & Etnier, 2000; McDonald & Hodgdon,
2012; Reed & Ones, 2006). For example, Reed and Ones (2006) reported that the average effect
size for acute aerobic exercise on positive activated affect was .47 (dcorr).
A growing body of evidence suggests that greater physiological and psychological
benefits occur if exercise takes place in a natural environment (termed green exercise; Barton &
Pretty, 2010; Gladwell, Brown, Wood, Sandercock, & Barton, 2013; Thompson Coon et al.,
2011). For example, acute bouts of green exercise have been shown to facilitate increases in
happiness (Yeh, Stone, Churchill, Brymer, & Davids, 2017), vigour (Song, Ikei, Igarashi,
Takagaki, & Miyazaki, 2015), and self-esteem (Pretty, Peacock, Sellens, & Griffin, 2005).
Moreover, when Mackay and Neill (2010) compared the anxiolytic effects of different exercise
types they found a larger effect size for mountain biking (d = 1.02) than road cycling (d = 0.84).
Similarly, (Akers et al., 2012) found that during cycling, green scenery elicited greater
improvements in mood compared with grey scenery. Importantly, psychological benefits are
elicited from as little as 5 minutes (Barton & Pretty, 2010) to 30 minutes (Shanahan et al., 2016)
of green exercise. Although a number of theories have been proposed, such as the Biophilia
MANUSCRIP
T
ACCEPTED
ACCEPTED MANUSCRIPTEXPECTANCY EFFECTS IN GREEN EXERCISE 2
Hypothesis (Wilson, 1984) and Attention Restoration Theory (Kaplan & Kaplan, 1989), the
mechanisms for the additional psychological benefits of green exercise compared to
urban/indoor exercise are still unclear.
A small number of studies have explored the role of individuals’ thoughts and feelings on
green exercise behaviours (Calogiuri & Elliott, 2017; Curry, Crone, James, & Gidlow, 2011;
Groshong, Stanis, Kaczynski, Hipp, & Besenyi, 2017; Loureiro et al., 2014). For example,
Calogiuri and Elliott (2017) found that for Norwegian adults, experiencing nature was the
second-most important motive for exercise, exceeded only by convenience. Furthermore,
individuals who have a higher connectedness with nature tend to spend more time in nature, and
subsequently do more green exercise (Flowers, Freeman, & Gladwell, 2016). Until recently,
however, there has been no established measure to assess how individuals feel about green
exercise as a distinct mode of physical activity.
Based upon the Theory of Planned Behaviour (Ajzen, 1991), Flowers, Freeman, and
Gladwell (2017) developed the Beliefs about Green Exercise Questionnaire (BAGE) to assess
attitudes, subjective norms, and perceived behavioural control towards green exercise. Some
items within the attitudes sub-scale assess how individuals feel about performing green exercise
(i.e. is it beneficial? Is it pleasant?), and thus may provide key insights into how people expect to
feel following the activity. Moreover, evidence from the wider physical activity literature shows
an inherent link between attitudes and exercise behaviours (Chatzisarantis, Hagger, Biddle, &
Smith, 2005; Rhodes, 2009). Yet, no research to our knowledge has explored whether attitudes
towards green exercise influence acute psychological outcomes.
In the exercise domain, some researchers have postulated that expectancy beliefs play a
role in the acute psychological benefits of exercise (Bérdi, Köteles, Szabó, & Bárdos, 2011;
MANUSCRIP
T
ACCEPTED
ACCEPTED MANUSCRIPTEXPECTANCY EFFECTS IN GREEN EXERCISE 3
Lindheimer, O'Connor, & Dishman, 2015; Ojanen, 1994; Szabo, 2013). Empirically, researchers
have adopted expectancy manipulations to examine the possible role of expectancy effects. For
example, Desharnais, Jobin, Cote, Levesque, and Godin (1993) manipulated expectations to
elicit greater improvements in self-esteem following a four-week exercise program. The authors
used an authoritative statement to manipulate expectations, which is the most commonly used
technique within the exercise domain (Crum & Langer, 2007; Desharnais et al., 1993; Helfer et
al., 2014; Kwan, Stevens, & Bryan, 2017; Lindheimer, O'Connor, McCully, & Dishman, 2017).
Posters (Stanforth, Steinhardt, Mackert, Stanforth, & Gloria, 2011), videos (Mothes et al., 2017),
and sham equipment (Lindheimer et al., 2017; Mothes et al., 2017; Reed, 2014) have also been
used to explore the role of expectancy effects in exercise outcomes.
Some evidence indicates that expectations play a role in some of the outcomes of
common activities such as running (Berger, Owen, Motl, & Parks, 1998; Kwan et al., 2017;
Szabo & Abraham, 2013) and cycling (Helfer et al., 2014; Mothes et al., 2017). For example,
Helfer et al. (2014) explored the role of expectancy effects on mood following 10-minutes of
light-intensity cycling. Participants (N = 140) were randomly assigned to one of four groups in a
2 (no expectation vs affective expectation) x 2 (no elaboration vs elaboration) between-group
design. The affective groups were told that physical activity is good for happiness, mood and
self-esteem. The elaboration groups were asked to write the information they had received as a
recall task. There was a significant post-exercise main effect for expectation (ηp2 = .06), but not
for elaboration or an interaction of the two. This finding is supported by recent reviews (Bérdi et
al., 2011; Lindheimer et al., 2015; Szabo, 2013). In contrast, the expectancy effect has been
more elusive in studies using 30-minute bouts of cycling (Lindheimer et al., 2017; Mothes et al.,
2017). Within these studies, the strength of expectancy manipulation and exercise type/duration
MANUSCRIP
T
ACCEPTED
ACCEPTED MANUSCRIPTEXPECTANCY EFFECTS IN GREEN EXERCISE 4
were noted as possible reasons for non-significant effects. Helfer et al. (2014) suggested that
aversive experiences, such as longer moderate intensity exercise that may cause muscular pain or
discomfort, are less likely to be influenced by expectation manipulations.
Green Mind Theory, which outlines reciprocal links between each of human behaviour,
mind, brain and body, and natural and social environments, forwards that expectancy effects
stemming from beliefs are likely to influence the therapeutic outcomes of spending time in
nature (Pretty, Rogerson, & Barton, 2017). For example, Pretty and colleagues proposed that
healing gardens in hospitals, promoted through a good patient-practitioner relationship, may
induce health related expectancy effects. However, researchers have yet to examine whether
expectations play a role in the acute psychological benefits of green exercise, and if modifying
expectations can enhance those outcomes further.
Measuring attitudes (as a proxy for expectations) before and after green exercise research
may provide important insight into the role of expectancy effects. As studies have shown links
between affective states and outdoor exercise (Focht, 2009; Groshong et al., 2017; Lacharite-
Lemieux, Brunelle, & Dionne, 2015), then changes in affective attitudes may manifest as
additional benefits. More generally though, exploring the role of expectancy effects in green
exercise is important for public health. For example, if attitudes are related to green exercise
outcomes, then promoting the activity may enhance actual outcomes. This is worthwhile as post-
exercise invigoration can increase the likelihood of repeating the behaviour (Ekkekakis, Parfitt,
& Petruzzello, 2011; Focht, 2009; Kwan & Bryan, 2010).
The preliminary aim was to examine if exercise in a natural environment would facilitate
greater psychological benefits than indoor exercise. We hypothesised that exercising in a natural
environment would elicit greater psychological benefits than indoor exercise. The primary aim
MANUSCRIP
T
ACCEPTED
ACCEPTED MANUSCRIPTEXPECTANCY EFFECTS IN GREEN EXERCISE 5
was to examine if expectancy effects play a role in the acute psychological benefits of green
exercise. We hypothesised that compared to a control condition, watching a promotional video
about green exercise before undertaking exercise in a green environment would elicit greater
psychological benefits (vigour and self-esteem), and a change in attitudes (as a proxy for
expectations) towards green exercise may play a role. The secondary aim of the study was to
examine the effect of the same video on indoor exercisers; we hypothesised that watching the
video would result in suppressed self-esteem and vigour.
Method
Participants
The sample size was based on an a priori power analysis focused on testing the primary
aim (G-power version 3.1; Faul, Erdfelder, Lang, & Buchner, 2007). An expected effect size (f =
0.25) was derived from an equivalent effect size (ηp2 = 0.06), observed in previous research
(Helfer et al., 2014). This was entered along with power at 0.8 and an alpha of .05. This
indicated a sample size of 68. Undergraduate students (19 women, 41 men, Mage = 19.9 years,
SD = 4.26, age range 18-51 years) were recruited using opportunistic sampling (poster and email
advertisements) at the University of Essex. Participants reported their ethnicity as White (67%),
Asian (13%), Mixed (12%), or Other (8%).
Design
A single-blind randomised mixed-model design was used: participants cycled at a
moderate-intensity for 15 minutes in one of four groups. Treatment (green vs indoor) and
condition (expectancy vs control) were the two between-group factors; those in the green
treatment (i.e. green exercisers) completed the cycling task in a green-outdoor environment, and
those in the indoor treatment completed the entire task inside a laboratory. Further, those in the
MANUSCRIP
T
ACCEPTED
ACCEPTED MANUSCRIPTEXPECTANCY EFFECTS IN GREEN EXERCISE 6
expectancy condition were shown a promotional video of green exercise, and those in the control
condition were not. Measures of self-esteem, and vigour and were taken pre- and post-exercise
as repeated measures dependent variables (as described below). Measures of attitudes (as a
proxy for expectations) were taken pre- and post-exercise as a manipulation check to confirm
that the video had the anticipated effect.
Treatments. Treatments were chosen to replicate that of a previous study (Rogerson,
Gladwell, Gallagher, & Barton, 2016). For the indoor treatment, stationary cycling was
completed in a laboratory with a view facing a light grey painted wall (Fig 1). Equipment,
furniture, and objects were moved from peripheral vision. For the green treatment, stationary
cycling was completed on the edge of a large sports field. This consisted of a mostly flat and
grass covered expansive area with interspersed trees and hedge perimeter (Fig 1). In both
treatments, the experimenter stood diagonally behind the ergometer 3m away.
INSERT FIGURE 1
Conditions. Those in the expectancy condition were shown a promotional video of
green exercise. This was designed to highlight the benefits of exercising in a natural
environment, and manipulate expectations regarding the outcomes of acute green exercise. The
video was created using Microsoft PowerPoint 2016 (Redmond, WA, USA). The 3-minute (11
slides), silent video contained a mixture of text and images amongst a bold green background.
Information – from credible sources such as the National Health Service and World Health
Organisation – was provided about the health and emotional consequences of green exercise.
Moreover, the video contained advice on how to perform green exercise.
To test the effectiveness of the promotional video, a pilot study was conducted in a
university lecture theatre. Undergraduate students (12 women, 19 men, Mage = 21.3 years, SD =
MANUSCRIP
T
ACCEPTED
ACCEPTED MANUSCRIPTEXPECTANCY EFFECTS IN GREEN EXERCISE 7
2.53, age range: 20-34 years) were recruited in a lecture at the University of Essex. Participants
reported their ethnicity as White (87%), Black (10%) or Mixed (3%). Participants were asked to
complete the attitudes measure (described later) before and after watching the promotional video.
A paired-samples t-test revealed significant increases in attitudes (t30 = -3.56, p = .001, d = .31).
Procedure
The research was approved by the University of Essex Research Ethics Committee. The
main study was conducted during the winter months (October 2016 to February 2017).
Participants were divided into one of four-groups using a block approach (block size 60, with a
1:1:1:1 ratio). Each timeslot for participation had been pre-determined by the investigator as a
treatment (green or indoor) and condition (expectancy or control), however, this was blinded to
participants during sign-up. On a first come, first serve basis, participants self-selected a
timeslot for participation and told to bring suitable clothing for indoor and outdoor
exercise. Upon arrival at the laboratory, participants read an information sheet and provided
informed consent. Next, height and weight were recorded and a Polar T31 chest strap was fitted
(Polar Electro Oy, Kempele, Finland).
At this point, the green treatment groups were escorted to a sports pavilion on the edge of
the sports field (approximately a 3-minute walk), whereas the indoor treatment groups remained
in the laboratory (Fig 2). All participants completed the baseline and control measures on a Dell
Inspiron 13 7000 laptop (Dell Inc, Round Rock, Texas, USA), using Qualtrics research software
(Qualtrics, Provo, Utah, USA); for those in the outdoor condition this was in the sports pavilion,
whereas for those in the indoor this was in the laboratory. Resting heart rate was recorded at its
lowest point within 60 seconds after participants had completed the questionnaires while they
remained seated.
MANUSCRIP
T
ACCEPTED
ACCEPTED MANUSCRIPTEXPECTANCY EFFECTS IN GREEN EXERCISE 8
Prior to cycling, those in the green condition were escorted outside the pavilion and all
participants were given time, and help if needed, to adjust the saddle height. Within a single
experimental session, participants cycled twice on a CatEye ergociser (EC-1600, CatEye Co.
Ltd., Osaka, Japan) ergometer. First, participants performed a submaximal fitness test based on
the YMCA protocol (Golding, Myers, & Sinning, 1989). This test required cycling at
approximately 50 rpm for 9 minutes. At three-minute intervals, and in accordance with heart
rate readings, the resistance of the bike automatically increased from low to high relative
resistance. The resistance increased on 2 occasions. The first test was to familiarise participants
with using the ergometer and ascertain the data needed to calculate moderate-intensity for the
second bout of cycling.
Between the bouts of cycling, participants were escorted back to the desk where they
completed the baseline measures. For the green treatment, this involved escorting participants
back into the sports pavilion. During this period, those in the expectancy condition were shown
the promotional video. Time was also allocated for rest: up to 10 minutes of just sitting for those
who did not watch the promotional video, and up to 10 minutes including 3 minutes for those in
the video condition. However, the time was less if heart rate recovered to within 15 beats per
minute of their resting heart rate, which was the case for 37 (62%) participants.
After resting, participants were escorted back to the ergometer. For the second
(experimental) bout of cycling, the bike was set to an intensity that represented 50% heart rate
reserve (Garber et al., 2011). This was calculated using resting heart rate and data collected from
the submaximal test. Consistent with Rogerson, Gladwell, et al. (2016), the second bout lasted
15 minutes, and participants were free to choose cadence; the bike automatically adjusted
resistance to maintain a constant power output in line with calculated moderate-intensity values.
MANUSCRIP
T
ACCEPTED
ACCEPTED MANUSCRIPTEXPECTANCY EFFECTS IN GREEN EXERCISE 9
Unlike the first test, the ergometer screen was blanked out to prompt participants to view
forwards and experience the environment. At 7.5 minutes, perceived exertion was recorded (see
below). Finally, at the same location as they completed the baseline measures, participants
repeated the measures of attitudes, self-esteem and vigour, removed the heart-rate monitor, and
were debriefed about the design, aims and hypotheses of the research. Outdoor temperature was
recorded using data provided by the UK's National Meteorological Service.
INSERT FIGURE 2
Measures
Physical activity. Physical activity was assessed using two self-report single-item
measures. The Single-item Physical Activity Screening Measure (Zwolinsky, McKenna, Pringle,
Widdop, & Griffiths, 2015) assessed general physical activity, whereas a modified version
assessed green exercise. The wording of the general physical activity question was ‘In the past
week, on how many days have you done a total of 30 minutes or more of physical activity, which
was enough to raise your breathing rate. This may include sport, exercise, and brisk walking or
cycling for recreation or to get to and from places, but should not include housework or physical
activity that may be part of your job’. For green exercise, participants were asked ‘In the past
week, on how many days have you done physical activity in the presence of a natural
environment, which was enough to raise your breathing rate. This may include activities such as
brisk walking/jogging in a park, cycling along a canal path, or playing sport’. Both items
captured the number of active days per week on a scale from 0 to 7.
Perceived exertion. Perceived exertion was measured using the Rating of Perceived
Exertion scale (Borg, 1982). The scale consists of 15 vertically aligned numbers (ranging from 6
‘no exertion’ to 20 ‘maximal exertion’) that allows individuals to subjectively rate their level of
MANUSCRIP
T
ACCEPTED
ACCEPTED MANUSCRIPTEXPECTANCY EFFECTS IN GREEN EXERCISE 10
exertion during exercise. This is widely used in acute exercise research (Lindheimer et al., 2017;
Mothes et al., 2017; Rogerson, Gladwell, et al., 2016), and has been tested for reliability with
physiological measures of heart rate, blood lactate, % VO2max, VO2, and respiratory rate (Chen,
Fan, & Moe, 2002).
Attitudes to green exercise. Attitudes were assessed with the five-item attitudes sub-
scale of the Belief about Green Exercise questionnaire (BAGE; Flowers et al., 2017). The
BAGE was developed to assess how people feel regarding physical activity in the presence of
natural environments, and was demonstrated to have strong psychometric properties. Items were
preceded with the following statement ‘Green Exercise is physical activity that takes place in the
presence of nature (e.g., parks, woodlands, sports fields etc)’ and scored from 1 to 7, with higher
scores reflecting more positive attitudes to green exercise. For example, ‘Doing green exercise
as part of my weekly physical activity is… (1) Unpleasant to (7) Pleasant’.
Self-esteem. Self-esteem was assessed using Rosenberg’s Self-Esteem Scale (Rosenberg,
1965), which is a 10-item scale. Each item consists of a brief statement (e.g., I feel that I have a
number of good qualities) and participants respond on a Likert scale ranging from (1) Strongly
Disagree to (4) Strongly Agree. The responses to five items are reverse scored so that higher
numbers reflect greater self-esteem. Self-esteem was recorded as the sum of all 10 items. The
Self-Esteem Scale has previously been used – and shown to be sensitive – in green exercise
research (Barton & Pretty, 2010),
Vigour. Vigour was assessed using five items from the shortened, 30-item version of the
Profile of Mood States (McNair, 1971; McNair, Lorr, & Droppleman, 1992). Participants
indicated how they felt ‘right now’ towards single-word descriptors of vigour (e.g., Lively),
using a Likert scale from (1) Not at all to (5) Extremely, therefore producing an overall score
MANUSCRIP
T
ACCEPTED
ACCEPTED MANUSCRIPTEXPECTANCY EFFECTS IN GREEN EXERCISE 11
between 5 and 25. The vigour sub-scale of the Profile of Mood States has previously been used
in expectancy research (Lindheimer et al., 2015), and has been shown to be sensitive to acute
bouts of cycling (Steptoe & Cox, 1988).
Data Analysis
Statistical analyses were carried out to test the preliminary, primary and secondary
hypotheses. Initially, analyses were conducted to ensure the groups were equivalent on five
variables identified as potential confounders: self-reported physical activity and green exercise
levels, perceived exertion, 50% HRR cycling intensity (W), and outdoor temperature during
experimental session. A series of two-way between-group ANOVAs were run to assess if there
were any condition and/or treatment differences between the four groups (N = 60) on each
potential confounder. For the manipulation check, tests were run to assess if the expectancy
manipulation had any effect on attitudes following acute exercise. Specifically, a mixed-model
ANOVA was run with condition and treatment as between-subjects independent variables, time
as a repeated measures variable, and attitudes as a dependant variable (N = 60).
To assess the overall model, a three-way mixed-model MANOVA was run with condition
and treatment as between-subjects independent variables, time as a repeated measures variable,
and vigour and self-esteem as dependant variables (N = 60). To further explore significant
effects, univariate tests were run individually for vigour (N = 60) and self-esteem (N = 60) with
condition, treatment and time as independent variables. Planned comparisons were then run to
test the preliminary (green exercise effect), primary (expectancy effect), and secondary (negative
expectancy effect) hypotheses. To test the preliminary hypothesis, the two control groups were
included in the analyses (N = 30), and tests were run individually for vigour and self-esteem.
MANUSCRIP
T
ACCEPTED
ACCEPTED MANUSCRIPTEXPECTANCY EFFECTS IN GREEN EXERCISE 12
Specifically, two mixed-model ANOVAs were run to assess if treatment (green control vs indoor
control) influenced change in psychological wellbeing over time (pre- and post-exercise).
To test the primary hypothesis, analyses were conducted to assess if the expectancy
manipulation induced additional psychological benefits over and above that of green exercise.
Only the green treatment groups were included (N = 30), and tests were run individually for self-
esteem and vigour (as dependent variables). Specifically, two mixed-model ANOVAs were run
to assess if condition (expectancy vs control) influenced self-esteem and vigour over time (pre-
and post-exercise).
To test the secondary hypothesis, analyses were conducted to examine if the expectancy
manipulation suppressed psychological wellbeing following indoor exercise. Only the indoor
treatment groups were included (N = 30), and tests were run individually for self-esteem and
vigour (as dependent variables). Specifically, two mixed-model ANOVAs were run to assess if
condition (expectancy vs control) influenced changes in self-esteem and vigour over time (pre-
and post-exercise). Significance was initially set at p < .05 but a Bonferroni-Holm’s correction
was applied to rule out the possibility of familywise error (Holm, 1979). All analyses were all
conducted using IBM SPSS 23 (Armonk, NY, USA).
Results
Descriptive and confounder analyses
All descriptive statistics are reported in Table 1. For outdoor temperature a two-way
between group ANOVA was run to assess if there were any treatment, condition or interactions
effect. There was a significant main effect of treatment on weather (F1,56 = 11.88, p < .01, ηp2
= .18), and no significant effects of condition (F1,56 = 0.61, p = .81, ηp2 = .00), and interaction
(F1,56 = 0.61, p = .81, ηp2 = .00). Those in the outdoor-treatment group had a mean temperature
MANUSCRIP
T
ACCEPTED
ACCEPTED MANUSCRIPTEXPECTANCY EFFECTS IN GREEN EXERCISE 13
of 10°C, whereas the indoor-treatment group had a mean temperature of 7°C outdoors, although
they remained indoors.
A series of two-way between-group ANOVAs were run to assess if there were any
condition, treatment, or interaction effects for each of the four remaining potential confounders.
For all remaining confounders, there were no significant main effects of treatment (Fs1, 56 = 0.01-
3.89, ps = .05-.35, ηp2 = .00-.04), condition (Fs1, 56 = 0.00-2.10, ps = .26-.70, ηp
2 = .00-.07), or
interactions (Fs1, 56 = 0.16-2.57, ps = .22-.63, ηp2 = .00-.04).
INSERT TABLE 1
Manipulation check
There was not a statistically significant interaction effect of time x treatment x condition
on attitudes (F1,54 = 2.17, p = .15, ηp2 = .04). For the primary analysis (expectancy effect), the
manipulation check revealed no significant interaction of time x treatment on attitudes (F1, 28 =
0.00, p = .97, ηp2 = .00) (Fig 4). For the secondary analysis (negative expectancy effect), the
manipulation check revealed a significant interaction effect of condition x time on attitudes (F1, 28
= 9.98, p = .00, ηp2 = .26); the indoor-expectancy group experienced a greater increase in
attitudes (M = 0.69, 95% CI 0.42-0.98), compared to the indoor-control group (M = 0.14, 95% CI
-0.14- 0.39) (Fig 5).
Mixed-model multivariate analysis of variance
Using Wilks’s statistic, there was a significant interaction of time x condition x treatment
on the combined dependent variables (vigour and self-esteem), Λ = 0.60, F2,53 = 17.97, p < .001,
ηp2 = .40. Additional univariate tests revealed significant interactions of time x condition x
treatment on vigour (F1,54 = 27.55, p = < .001, ηp2 = .34) and self-esteem (F1,54 = 6.10, p = 0.17,
MANUSCRIP
T
ACCEPTED
ACCEPTED MANUSCRIPTEXPECTANCY EFFECTS IN GREEN EXERCISE 14
ηp2 = .10) individually. To further explore these interactions, planned comparisons focused on
the preliminary, primary, and secondary hypotheses.
Preliminary hypothesis: the green exercise effect. Due to the Bonferroni-Holm’s
correction, there was a marginally significant interaction effect of treatment x time on vigour (F1,
28 = 4.49, p = .043, ηp2 = .14) (Fig 3); the green-control group experienced a greater improvement
in vigour (M = 2.00, 95% CI 1.06-2.94) than the indoor-control group (M = 0.60, 95% CI -0.46-
1.66). The interaction of time x treatment had no significant effect on self-esteem (F1, 28 = 0.31,
p = .58, ηp2 = .01) (Fig 3)i.
INSERT FIGURE 3
Primary hypothesis: the expectancy effect. The results indicate an expectancy effect;
significant interaction effects for condition x time were found for both vigour (F1, 28 = 12.96, p
= .00, ηp2 = .32) and self-esteem (F1, 28 = 5.69, p = .02, ηp
2 = .17) (Fig 4). The green-expectancy
group experienced a greater improvement in vigour (M = 4.13, 95% CI 3.27-4.99) compared to
the green-control group (M = 2.00, 95% CI 1.06-2.94). Similarly, a greater improvement in self-
esteem occurred in the green-expectancy group (M = 4.07, 95% CI 2.47-5.67) compared to the
green-control group (M = 1.93, 95% CI 0.80-2.99).
INSERT FIGURE 4
Secondary hypothesis: the negative expectancy effect. The results indicate a negative
expectancy effect; there was a significant interaction effect of condition x time on vigour (F1, 28 =
15.10, p = .00, ηp2 = .35) (Fig 5). The indoor-control group experienced an increase in vigour (M
= 0.60, 95% CI -0.46-1.66), whereas the indoor-expectancy group experienced a decrease in
vigour (M = -2.40, 95% CI -3.67- 1.13). No significant interaction effect for condition x time
MANUSCRIP
T
ACCEPTED
ACCEPTED MANUSCRIPTEXPECTANCY EFFECTS IN GREEN EXERCISE 15
was found for self-esteem, although there was a small-medium effect size (F1, 28 = 1.08, p = .31,
ηp2 = .03) (Fig 5).
INSERT FIGURE 5
Discussion
We explored the impact of a green exercise promotional video on vigour and self-esteem
following an acute bout of moderate-intensity exercise. The video was designed to inform
participants of the benefits of green exercise and modify expectations regarding the outcomes of
an acute bout of green exercise. Initially, our results provide further evidence for the therapeutic
outcomes of green exercise. Consistent with some expectancy research, when we showed the
video to green exercisers, the therapeutic outcomes were enhanced. This is important because it
shows that promotional tools may be used to enhance acute outcomes of green exercise. Further,
the very same video elicited a negative expectation effect amongst indoor exercisers, and
subsequently suppressed post exercise vigour.
Consistent with previous research (Barton, Bragg, Wood, & Pretty, 2016; Barton &
Pretty, 2010; Gladwell et al., 2013; Thompson Coon et al., 2011), the current findings provide
further evidence of the psychological benefits of green exercise. Specifically, participants in the
green control group experienced a 17% increase in vigour, whereas the indoor control group only
experienced a 5% increase in vigour. As there were no significant differences in perceived
exertion or power output during cycling, changes in vigour may be explained by environmental
conditions. Those individuals who exercised outdoors may have benefitted from the synergistic
effects of exercising in the presence of nature.
To our knowledge, this is the first study to explore the potential for expectancy effects to
enhance the benefits of green exercise. As with previous expectancy exercise research
MANUSCRIP
T
ACCEPTED
ACCEPTED MANUSCRIPTEXPECTANCY EFFECTS IN GREEN EXERCISE 16
(Desharnais et al., 1993; Helfer et al., 2014), we found that informing participants of the
psychological benefits of exercise induced a significant increase in psychological wellbeing.
This may be explained by psychological benefits of green exercise being related to both
conditioning and expectations. Previous research has shown that the expectancy effect of sham
painkillers (Amanzio & Benedetti, 1999) and oxygen (Benedetti, Durando, Giudetti, Pampallona,
& Vighetti, 2015) are related to a pre-conditioning of the actual therapeutic effect. In these
studies, participants experienced the active ingredient multiple times, prior to receiving a
placebo. After pre-conditioning occurred, an expectancy (placebo) effect was more likely to
appear following administration of an inert substance.
To assess for pre-conditioning in this study, we asked participants to report attitudes to
green exercise and green exercise levels. We are confident that prior to attending the experiment,
participants were pre-conditioned to the benefits of green exercise. Descriptive data (Table 1)
shows participants perform green exercise over twice per week on average, and also had strong
attitudes towards green exercise. This highlights a familiarity with doing green exercise and an
appreciation of the benefits. We propose that the green exercise and expectancy effects found in
this study are partly due to a pre-conditioning of the psychological benefits of green exercise.
Interestingly, we found both a significant environmental effect, and a marginally significant
positive expectancy effect. Perhaps, the expectancy manipulation in this study reminded the
participants that they were receiving a therapy, and thus heightened the conditioned response.
In this study, changes in attitudes did not serve as the mechanism for the enhanced
psychological wellbeing. There are several possible explanations for this. First, whilst the
attitudes dimension of the BAGE is a validated measure designed to capture beliefs about
behavioural outcomes of green exercise, it was not designed to capture expectations regarding
MANUSCRIP
T
ACCEPTED
ACCEPTED MANUSCRIPTEXPECTANCY EFFECTS IN GREEN EXERCISE 17
the acute psychological outcomes of green exercise. In this study, the attitudes measure of the
BAGE acted as a proxy for expectations, but perhaps it did not accurately capture subtle, yet
important changes in expectations. Second, although the findings are consistent with expectancy
effects, a change in expectations may not have served as the mechanism for improved outcomes.
Recent advances in placebo research suggest positive effects of some treatments can occur
through a variety of psychological, neurological, and biological mechanisms (Benedetti, 2014),
and it is possible that expectation is not a mechanism for green exercise. Finally, vigour and
self-esteem may have improved for reasons other than expectancy effect. For example, the
single-blind design and/or demand characteristics may have contributed to the significant
findings.
The indoor-expectancy group experienced suppressed psychological outcomes compared
to the indoor-control group. Instead of a conditioned response to a therapy, the negative
expectancy effect may have occurred through the rumination of an absent therapy or fear of
missing out. Previous research shows that the fear of missing out is associated with lower mood
states (Przybylski, Murayama, DeHaan, & Gladwell, 2013). In the indoor-expectancy group, the
video may have induced memories of green exercise, and created a dissonance between reality
and therapy (e.g., ‘the researchers have shown me a video about the benefits of green exercise, it
agrees with some of my previous experiences, and now they have asked me cycle in front of a
grey wall’). In support of this, attitudes to green exercise increased significantly more in the
indoor-treatment group compared to the indoor-control group, although this assumes that the
strong positive attitudes about green exercise are inherently opposite to negative attitudes about
indoor exercise (which we did not assess). However, we suspect that being shown a video of
green exercise before being made to cycle indoors (a less invigorating experience) may have
MANUSCRIP
T
ACCEPTED
ACCEPTED MANUSCRIPTEXPECTANCY EFFECTS IN GREEN EXERCISE 18
coerced participants to make a cognitive comparison about the mode of exercise and in turn
increased their attitudes to green exercise. In the absence of prior research relating to negative
expectancy effects in the green exercise domain, this speculative explanation warrants further
examination.
It is possible that demand characteristics played a role in the reported positive and
negative expectancy effects. Demand characteristics are an experimental artefact whereby
participants change their behaviour and/or responses based on their interpretation of the research
hypothesis (Orne, 1962). Although this can occur with all self-reported measures, our
experimental design may have led to different demand characteristics between groups. Although
the locations at which baseline measures were completed may have been susceptible to demand
characteristics, non-significant differences in baseline attitudes to green exercise lead us to
believe that demand characteristics were not present at this stage. However, they may have
occurred following the expectancy manipulation. Those in the expectancy groups were shown a
promotional video of green exercise, then asked to cycle in either an indoor or outdoor
environment. The belief about whether the environment in which they cycled facilitated or
inhibited psychological wellbeing may have altered how participant’s reported self-esteem and
vigour.
The current findings have some important implications for researchers and applied
practitioners. First, the findings emphasis that careful consideration of the methodological
design and an understanding of pre-existing conditioning and expectations are vital to ensure that
expectancy effects are accounted for in green exercise research. For example, we assessed
attitudes to perform green exercise using a validated questionnaire to increase our ability to
assess the expectancy effect. Second, acknowledgement of the negative expectancy effect in
MANUSCRIP
T
ACCEPTED
ACCEPTED MANUSCRIPTEXPECTANCY EFFECTS IN GREEN EXERCISE 19
exercise research will help shape a better understanding of the less well-known phenomena. For
example, if policy makers inform people of the benefits of particular types of exercise (such as
green exercise) but do not provide appropriate access or facilities to enable people to undertake
that exercise (such as safe, accessible green spaces), then it may be detrimental to psychological
wellbeing.
Despite the strengths of the research in providing important insight into green exercise,
some limitations should be acknowledged. First, although the study examined expectancy
effects, it did not assess other possible mechanisms for different outcomes between groups.
Using subjective measures, we cannot quantify how much of the expectancy effect was due to a
psychoneurological changes or demand characteristics. Second, although efforts were made to
create an authentic and controlled outdoor exercise experience that could be accurately compared
to indoor exercise, cycling on a stationary bike on the edge of a field is not a common occurrence
and may not replicate participants’ previous pleasant experience of green exercise. Third,
although effort was made to avoid demand characteristics, failure to blind test administrators to
the expectation condition may have had an effect. It was not possible to truly blind participants
to either condition (as they knew whether they had watched a video or not) nor treatment (as they
knew they had exercised indoors or outdoors), however, participants were blinded to the overall
design and aims of the study. Fourth, although a power analysis revealed we needed 68
participants for the study, we only recruited 60, therefore increasing the chance of a type-II error.
Fifth, as mentioned previously, the participants had high levels of baseline attitudes towards
green exercise, and green exercise levels. This may have been a consequence of the opportunistic
sampling method used in this study. Finally, although this study is one of the few to assess
attitudes before and after physical activity, the BAGE was designed to assess how individuals
MANUSCRIP
T
ACCEPTED
ACCEPTED MANUSCRIPTEXPECTANCY EFFECTS IN GREEN EXERCISE 20
feel about green exercise as a contributor to weekly physical activity and not how individuals
feel towards the acute psychological benefits of green exercise.
Further research is warranted to understand the mechanisms behind the effects of green
exercise, and to understand how promotional tools can be utilised to enhance outcomes. In green
exercise literature, a small number of studies (Aspinall, Mavros, Coyne, & Roe, 2015; Bratman,
Hamilton, Hahn, Daily, & Gross, 2015; He, Chen, & Yu, 2016) have begun to utilise
neurophysiological measures to explore the effect of green exercise on psychological wellbeing
objectively. For example, portable devices (such as Emotive EPOC; Emotiv Ltd, Hong Kong)
could be used to examine the impact of expectancy modification on brain activity during green
exercise. This technique may also help identify if a pre-conditioning of green exercise exists and
is represented as a heightened anticipatory rise in engagement and/or excitement. Future studies
should also consider blinding experimenters where possible and consider the impact of
environmental characteristics such as temperature and humidity during outdoor experimental
sessions.
In conclusion, this was the first study to assess the potential role of expectancy effects on
the psychological benefits of acute green exercise. The results indicated that an expectancy
manipulation can amplify the acute psychological benefits of green exercise. Using simple video
editing tools, and a previously designed environmental comparison (Rogerson, Gladwell, et al.,
2016), we improved the psychological outcomes of moderate-intensity cycling in a green setting.
As affective responses to moderate-intensity exercise have been shown to predict future
participation (Williams et al., 2008), this could be an effective way of improving physical
activity levels for the betterment of health and wellbeing and therefore holds great promise for
researchers, practitioners and policy makers.
MANUSCRIP
T
ACCEPTED
ACCEPTED MANUSCRIPTEXPECTANCY EFFECTS IN GREEN EXERCISE 21
References
Ajzen, I. (1991). The theory of planned behavior. Organizational behavior and human decision processes, 50(2), 179-211.
Akers, A., Barton, J., Cossey, R., Gainsford, P., Griffin, M., & Micklewright, D. (2012). Visual color perception in green exercise: positive effects on mood and perceived exertion. Environ Sci Technol, 46(16), 8661-8666. doi:10.1021/es301685g
Amanzio, M., & Benedetti, F. (1999). Neuropharmacological dissection of placebo analgesia: expectation-activated opioid systems versus conditioning-activated specific subsystems. J Neurosci, 19(1), 484-494.
Anderson, R. J., & Brice, S. (2011). The mood-enhancing benefits of exercise: Memory biases augment the effect. Psychology of Sport and Exercise, 12(2), 79-82. doi:10.1016/j.psychsport.2010.08.003
Arent, S. M., Landers, D. M., & Etnier, J. L. (2000). The effects of exercise on mood in older adults: A meta-analytic review. Journal of Aging and physical Activity, 8(4), 407-430.
Aspinall, P., Mavros, P., Coyne, R., & Roe, J. (2015). The urban brain: analysing outdoor physical activity with mobile EEG. Br J Sports Med, 49(4), 272-276. doi:10.1136/bjsports-2012-091877
Barton, J., Bragg, R., Wood, C., & Pretty, J. (2016). Green Exercise: Linking Nature, Health and Well-being: Taylor & Francis.
Barton, J., & Pretty, J. (2010). What is the Best Dose of Nature and Green Exercise lor Improving Mental Health? A Multi-Study Analysis. Envonmental Science & Technology, 44, 3947-3955.
Benedetti, F. (2014). Placebo Effects: Oxford University Press. Benedetti, F., Durando, J., Giudetti, L., Pampallona, A., & Vighetti, S. (2015). High-altitude
headache: the effects of real vs sham oxygen administration. Pain, 156(11), 2326-2336. doi:10.1097/j.pain.0000000000000288
Bérdi, M., Köteles, F., Szabó, A., & Bárdos, G. (2011). Placebo Effects in Sport and Exercise: A Meta-Analysis. European Journal of Mental Health, 6(2), 196-212. doi:10.5708/ejmh.6.2011.2.5
Berger, B. G., & Motl, R. W. (2000). Exercise and mood: A selective review and synthesis of research employing the profile of mood states. Journal of Applied Sport Psychology, 12(1), 69-92.
Berger, B. G., Owen, D. R., Motl, R. W., & Parks, L. (1998). Relationship between expectancy of psychological benefits and mood alteration in joggers. International Journal of Sport Psychology.
Borg, G. A. (1982). Psychophysical bases of perceived exertion. Med Sci Sports Exerc, 14(5), 377-381.
Bratman, G. N., Hamilton, J. P., Hahn, K. S., Daily, G. C., & Gross, J. J. (2015). Nature experience reduces rumination and subgenual prefrontal cortex activation. Proc Natl Acad Sci U S A, 112(28), 8567-8572. doi:10.1073/pnas.1510459112
Calogiuri, G., & Elliott, L. R. (2017). Why Do People Exercise in Natural Environments? Norwegian Adults' Motives for Nature-, Gym-, and Sports-Based Exercise. Int J Environ Res Public Health, 14(4). doi:10.3390/ijerph14040377
MANUSCRIP
T
ACCEPTED
ACCEPTED MANUSCRIPTEXPECTANCY EFFECTS IN GREEN EXERCISE 22
Chatzisarantis, N. L., Hagger, M. S., Biddle, S. J., & Smith, B. (2005). The stability of the attitude-intention relationship in the context of physical activity. J Sports Sci, 23(1), 49-61. doi:10.1080/02640410410001730070
Chen, M. J., Fan, X., & Moe, S. T. (2002). Criterion-related validity of the Borg ratings of perceived exertion scale in healthy individuals: a meta-analysis. J Sports Sci, 20(11), 873-899. doi:10.1080/026404102320761787
Crum, A. J., & Langer, E. J. (2007). Mind-set matters: exercise and the placebo effect. Psychol Sci, 18(2), 165-171. doi:10.1111/j.1467-9280.2007.01867.x
Curry, N. R., Crone, D., James, D., & Gidlow, C. (2011). Factors influencing participation in outdoor physical activity promotion schemes: the case of South Staffordshire, England. Leisure Studies, 31(4), 447-463. doi:10.1080/02614367.2011.600322
Desharnais, R., Jobin, J., Cote, C., Levesque, L., & Godin, G. (1993). Aerobic exercise and the placebo effect: a controlled study. Psychosom Med, 55(2), 149-154.
Ekkekakis, P., Parfitt, G., & Petruzzello, S. J. (2011). The pleasure and displeasure people feel when they exercise at different intensities: decennial update and progress towards a tripartite rationale for exercise intensity prescription. Sports Med, 41(8), 641-671. doi:10.2165/11590680-000000000-00000
Ensari, I., Greenlee, T. A., Motl, R. W., & Petruzzello, S. J. (2015). Meta-Analysis of Acute Exercise Effects on State Anxiety: An Update of Randomized Controlled Trials over the Past 25 Years. Depress Anxiety, 32(8), 624-634. doi:10.1002/da.22370
Faul, F., Erdfelder, E., Lang, A.-G., & Buchner, A. (2007). G*Power 3: A flexible statistical power analysis program for the social, behavioral, and biomedical sciences. Behavior research methods, 39(2), 175-191. doi:10.3758/bf03193146
Flowers, E. P., Freeman, P., & Gladwell, V. F. (2016). A cross-sectional study examining predictors of visit frequency to local green space and the impact this has on physical activity levels. BMC Public Health, 16, 420. doi:10.1186/s12889-016-3050-9
Flowers, E. P., Freeman, P., & Gladwell, V. F. (2017). The Development of Three Questionnaires to Assess Beliefs about Green Exercise. Int J Environ Res Public Health, 14(10). doi:10.3390/ijerph14101172
Focht, B. C. (2009). Brief walks in outdoor and laboratory environments: effects on affective responses, enjoyment, and intentions to walk for exercise. Res Q Exerc Sport, 80(3), 611-620. doi:10.1080/02701367.2009.10599600
Fox, K. R. (2000). The effects of exercise on self-perceptions and self-esteem. Physical activity and psychological well-being, 13, 81-118.
Garber, C. E., Blissmer, B., Deschenes, M. R., Franklin, B. A., Lamonte, M. J., Lee, I.-M., . . . Swain, D. P. (2011). Quantity and quality of exercise for developing and maintaining cardiorespiratory, musculoskeletal, and neuromotor fitness in apparently healthy adults: guidance for prescribing exercise. Medicine & Science in Sports & Exercise, 43(7), 1334-1359.
Gladwell, V. F., Brown, D. K., Wood, C., Sandercock, G. R., & Barton, J. L. (2013). The great outdoors: how a green exercise environment can benefit all. Extrem Physiol Med, 2(1), 3. doi:10.1186/2046-7648-2-3
Golding, L. A., Myers, C. R., & Sinning, W. E. (1989). Y's Way to Physical Fitness: The Complete Guide to Fitness Testing and Instruction: YMCA of the USA.
Groshong, L., Stanis, S. A., Kaczynski, A. T., Hipp, J. A., & Besenyi, G. M. (2017). Exploring Attitudes, Perceived Norms, and Personal Agency: Insights Into Theory-Based Messages
MANUSCRIP
T
ACCEPTED
ACCEPTED MANUSCRIPTEXPECTANCY EFFECTS IN GREEN EXERCISE 23
to Encourage Park-Based Physical Activity in Low-Income Urban Neighborhoods. J Phys Act Health, 14(2), 108-116. doi:10.1123/jpah.2016-0069
He, Y., Chen, Z., & Yu, Y. (2016). Visual Experience in Natural Environment Promotes Better Brain Functions Than Built Environment? Paper presented at the Advances in Cognitive Neurodynamics (V): Proceedings of the Fifth International Conference on Cognitive Neurodynamics - 2015.
Helfer, S. G., Elhai, J. D., & Geers, A. L. (2014). Affect and Exercise Positive Affective Expectations Can Increase Post-Exercise Mood and Exercise Intentions. Ann Behav Med, 49(2).
Holm, S. (1979). A Simple Sequentially Rejective Multiple Test Procedure. Scandinavian Journal of Statistics, 6(2), 65-70.
Kaplan, R., & Kaplan, S. (1989). The Experience of Nature: A Psychological Perspective: Cambridge University Press.
Kwan, B. M., & Bryan, A. D. (2010). Affective response to exercise as a component of exercise motivation: Attitudes, norms, self-efficacy, and temporal stability of intentions. Psychology of Sport and Exercise, 11(1), 71-79.
Kwan, B. M., Stevens, C. J., & Bryan, A. D. (2017). What to expect when you're exercising: An experimental test of the anticipated affect-exercise relationship. Health Psychol, 36(4), 309-319. doi:10.1037/hea0000453
Lacharite-Lemieux, M., Brunelle, J. P., & Dionne, I. J. (2015). Adherence to exercise and affective responses: comparison between outdoor and indoor training. Menopause, 22(7), 731-740. doi:10.1097/GME.0000000000000366
Lindheimer, J. B., O'Connor, P. J., & Dishman, R. K. (2015). Quantifying the placebo effect in psychological outcomes of exercise training: a meta-analysis of randomized trials. Sports Med, 45(5), 693-711. doi:10.1007/s40279-015-0303-1
Lindheimer, J. B., O'Connor, P. J., McCully, K. K., & Dishman, R. K. (2017). The Effect of Light-Intensity Cycling on Mood and Working Memory in Response to a Randomized, Placebo-Controlled Design. Psychosom Med, 79(2), 243-253. doi:10.1097/PSY.0000000000000381
Loureiro, A., Veloso, S., Rebola, F., Olivos, P., Lima, M. L., Aragonés, J. I., & de Lisboa, U. (2014). Outdoor exercise and connectedness with nature: relation to wellbeing.
Mackay, G. J., & Neill, J. T. (2010). The effect of “green exercise” on state anxiety and the role of exercise duration, intensity, and greenness: A quasi-experimental study. Psychology of Sport and Exercise, 11(3), 238-245. doi:10.1016/j.psychsport.2010.01.002
McDonald, D. G., & Hodgdon, J. A. (2012). The Psychological Effects of Aerobic Fitness Training: Research and Theory: Springer New York.
McNair, D. M. (1971). Manual profile of mood states: Educational & Industrial testing service. McNair, D. M., Lorr, M., & Droppleman, L. F. (1992). Profile of mood states: Educational and
industrial testing service San Diego, CA. Mothes, H., Leukel, C., Jo, H. G., Seelig, H., Schmidt, S., & Fuchs, R. (2017). Expectations
affect psychological and neurophysiological benefits even after a single bout of exercise. J Behav Med, 40(2), 293-306. doi:10.1007/s10865-016-9781-3
Ojanen, M. (1994). Can the true effects of exercise on psychological variables be separated from placebo effects? International Journal of Sport Psychology, 25(1), 63-80.
MANUSCRIP
T
ACCEPTED
ACCEPTED MANUSCRIPTEXPECTANCY EFFECTS IN GREEN EXERCISE 24
Orne, M. T. (1962). On the social psychology of the psychological experiment: With particular reference to demand characteristics and their implications. American psychologist, 17(11), 776.
Petruzzello, S. J., Landers, D. M., Hatfield, B. D., Kubitz, K. A., & Salazar, W. (1991). A meta-analysis on the anxiety-reducing effects of acute and chronic exercise. Outcomes and mechanisms. Sports Med, 11(3), 143-182.
Petruzzello, S. J., Snook, E. M., Gliottoni, R. C., & Motl, R. W. (2009). Anxiety and mood changes associated with acute cycling in persons with multiple sclerosis. Anxiety Stress Coping, 22(3), 297-307. doi:10.1080/10615800802441245
Pretty, J., Peacock, J., Sellens, M., & Griffin, M. (2005). The mental and physical health outcomes of green exercise. Int J Environ Health Res, 15(5), 319-337. doi:10.1080/09603120500155963
Pretty, J., Rogerson, M., & Barton, J. (2017). Green Mind Theory: How Brain-Body-Behaviour Links into Natural and Social Environments for Healthy Habits. Int J Environ Res Public Health, 14(7). doi:10.3390/ijerph14070706
Przybylski, A. K., Murayama, K., DeHaan, C. R., & Gladwell, V. (2013). Motivational, emotional, and behavioral correlates of fear of missing out. Computers in Human Behavior, 29(4), 1841-1848. doi:10.1016/j.chb.2013.02.014
Reed, J. (2014). Effect of Placebo-Induced Changes in Expectancies on Self-Reported Affect Associated with Yoga Practice. Journal of Sport Behaviour, 37(3), 268-285.
Reed, J., & Ones, D. S. (2006). The effect of acute aerobic exercise on positive activated affect: A meta-analysis. Psychology of Sport and Exercise, 7(5), 477-514. doi:10.1016/j.psychsport.2005.11.003
Rhodes, R. E. (2009). A Review and Meta-Analysis of Affective Judgments and Physical Activity in Adult Populations. doi:10.1007/s12160-009-9147-y)
Rogerson, M., Brown, D. K., Sandercock, G., Wooller, J. J., & Barton, J. (2016). A comparison of four typical green exercise environments and prediction of psychological health outcomes. Perspect Public Health, 136(3), 171-180. doi:10.1177/1757913915589845
Rogerson, M., Gladwell, V. F., Gallagher, D. J., & Barton, J. L. (2016). Influences of Green Outdoors versus Indoors Environmental Settings on Psychological and Social Outcomes of Controlled Exercise. Int J Environ Res Public Health, 13(4), 363. doi:10.3390/ijerph13040363
Rosenberg, M. (1965). Rosenberg self-esteem scale (RSE). Acceptance and commitment therapy. Measures package, 61, 52.
Shanahan, D. F., Bush, R., Gaston, K. J., Lin, B. B., Dean, J., Barber, E., & Fuller, R. A. (2016). Health Benefits from Nature Experiences Depend on Dose. Sci Rep, 6, 28551. doi:10.1038/srep28551
Song, C., Ikei, H., Igarashi, M., Takagaki, M., & Miyazaki, Y. (2015). Physiological and Psychological Effects of a Walk in Urban Parks in Fall. Int J Environ Res Public Health, 12(11), 14216-14228. doi:10.3390/ijerph121114216
Spence, J. C., McGannon, K. R., & Poon, P. (2005). The effect of exercise on global self-esteem: A quantitative review. Journal of Sport and Exercise Psychology, 27(3), 311-334.
Stanforth, D., Steinhardt, M., Mackert, M., Stanforth, P. R., & Gloria, C. T. (2011). An investigation of exercise and the placebo effect. Am J Health Behav, 35(3), 257-268.
Steptoe, A., & Cox, S. (1988). Acute effects of aerobic exercise on mood. Health Psychol, 7(4), 329-340.
MANUSCRIP
T
ACCEPTED
ACCEPTED MANUSCRIPTEXPECTANCY EFFECTS IN GREEN EXERCISE 25
Stonerock, G. L., Hoffman, B. M., Smith, P. J., & Blumenthal, J. A. (2015). Exercise as treatment for anxiety: systematic review and analysis. Annals of Behavioral Medicine, 49(4), 542-556.
Szabo, A. (2013). Acute psychological benefits of exercise: reconsideration of the placebo effect. J Ment Health, 22(5), 449-455. doi:10.3109/09638237.2012.734657
Szabo, A., & Abraham, J. (2013). The psychological benefits of recreational running: a field study. Psychol Health Med, 18(3), 251-261. doi:10.1080/13548506.2012.701755
Thompson Coon, J., Boddy, K., Stein, K., Whear, R., Barton, J., & Depledge, M. H. (2011). Does participating in physical activity in outdoor natural environments have a greater effect on physical and mental wellbeing than physical activity indoors? A systematic review. Environ Sci Technol, 45(5), 1761-1772. doi:10.1021/es102947t
Williams, D. M., Dunsiger, S., Ciccolo, J. T., Lewis, B. A., Albrecht, A. E., & Marcus, B. H. (2008). Acute Affective Response to a Moderate-intensity Exercise Stimulus Predicts Physical Activity Participation 6 and 12 Months Later. Psychol Sport Exerc, 9(3), 231-245. doi:10.1016/j.psychsport.2007.04.002
Wilson, E. O. (1984). Biophilia: Harvard University Press. Yeh, H. P., Stone, J. A., Churchill, S. M., Brymer, E., & Davids, K. (2017). Physical and
Emotional Benefits of Different Exercise Environments Designed for Treadmill Running. Int J Environ Res Public Health, 14(7). doi:10.3390/ijerph14070752
Yeung, R. R. (1996). The acute effects of exercise on mood state. J Psychosom Res, 40(2), 123-141.
Zwolinsky, S., McKenna, J., Pringle, A., Widdop, P., & Griffiths, C. (2015). Physical activity assessment for public health: efficacious use of the single-item measure. Public health, 129(12), 1630-1636.
MANUSCRIP
T
ACCEPTED
ACCEPTED MANUSCRIPTEXPECTANCY EFFECTS IN GREEN EXERCISE 26
Footnotes
i. Additional analyses revealed that attitudes do not mediate the relationship between the
independent variables and outcomes.
MANUSCRIP
T
ACCEPTED
ACCEPTED MANUSCRIPTEXPECTANCY EFFECTS IN GREEN EXERCISE 27
Table 1
Descriptive Statistics
Green (N = 30)
Expectancy (N = 15) Control (N = 15)
M (SD) M (SD)
Age (yrs) 19.67 (1.23) 19.53 (1.64)
Physical activity 4.33 (1.76) 4.60 (1.81)
Green exercise 3.13 (2.45) 2.87 (2.13)
Body Mass Index 22.84 (1.98) 24.46 (4.68)
Cycling (Watts) 121.60 (40.36) 109.47 (33.66)
RPE (7-minutes) 11.20 (1.57) 11.73 (2.09)
Temperature (°C) 9.73 (3.43) 9.73 (3.26)
Pre Attitudes 5.67 (0.70) 5.13 (1.19)
Post Attitudes 6.22 (0.67) 5.68 (0.59)
Pre Self-esteem 32.40 (4.79) 27.80 (2.21)
Post Self-esteem 36.47 (2.92) 29.73 (2.15)
Pre Vigour 11.67 (3.11) 11.87 (3.58)
Post Vigour 15.80 (2.98) 13.87 (3.14) Grey (N = 30)
Expectancy (N = 15) Control (N = 15)
M (SD) M (SD)
Age (yrs) 21.13 (8.31) 19.33 (1.05)
Physical activity 3.33 (1.84) 4.13 (1.73)
Green exercise 2.00 (1.51) 2.67 (1.76)
Body Mass Index 22.85 (2.73) 23.40 (2.40)
Cycling (Watts) 106.20 (35.98) 107.93 (31.13)
RPE (7-minutes) 12.40 (2.32) 12.40 (1.21)
Temperature (°C) 7.13 (2.83) 6.73 (3.04)
Pre Attitudes 5.58 (0.68) 5.59 (0.79)
Post Attitudes 6.28 (0.44) 5.73 (0.75)
Pre Self-esteem 29.00 (3.27) 32.27 (4.17)
Post Self-esteem 30.53 (2.90) 34.60 (4.21)
Pre Vigour 12.00 (5.25) 11.47 (4.45)
Post Vigour 9.6 (4.91) 12.07 (3.88) Note. Physical Activity = self-reported physical activity levels (days per week), Green Exercise = self-reported green exercise levels (days per week), RPE = rating of perceived exertion.
MANUSCRIP
T
ACCEPTED
ACCEPTED MANUSCRIPTEXPECTANCY EFFECTS IN GREEN EXERCISE 28
Figures
Figure 1. View from the cycle ergometer in the indoor and green conditions.
MANUSCRIP
T
ACCEPTED
ACCEPTED MANUSCRIPTEXPECTANCY EFFECTS IN GREEN EXERCISE 29
Figure 2. An illustration of the experimental procedure.
MANUSCRIP
T
ACCEPTED
ACCEPTED MANUSCRIPTEXPECTANCY EFFECTS IN GREEN EXERCISE 30
Figure 3. Treatment x time interaction for vigour and self-esteem (M and SD) between green and
indoor control groups (N = 30). Due to the Bonferroni-Holm’s correction, there was a
marginally significant interaction effect of treatment x time on vigour but not for self-esteem.
Figure 4. Condition x time interaction for vigour, self-esteem and attitudes (M and SD) amongst
green exercisers (N = 30). There was a significant interaction effect of condition x time on
vigour and self-esteem.
MANUSCRIP
T
ACCEPTED
ACCEPTED MANUSCRIPTEXPECTANCY EFFECTS IN GREEN EXERCISE 31
Figure 5. Condition x time interaction for vigour, self-esteem and attitudes (M and SD) amongst
indoor exercisers (N = 30). There was a significant interaction effect of condition x time on
vigour but not for self-esteem.
MANUSCRIP
T
ACCEPTED
ACCEPTED MANUSCRIPTHighlights
• We explored the impact of a green exercise promotional video on acute psychological outcomes of moderate-intensity exercise
• Green exercise can elicit greater acute psychological benefits than indoor exercise • Positive expectancy effects can enhance the acute psychological benefits of green exercise • Negative expectancy effects can diminish the acute psychological benefits of indoor exercise • Marketing green exercise can improve outcomes, which may increase green exercise
behaviours